This document provides recommended limits for aggregates used in concrete works. It includes 4 tables that specify: 1) physical and mechanical properties testing of aggregates, 2) contamination and reactivity testing, 3) total chloride and sulphate content limits in concrete, and 4) recommended size and gradings of aggregates. Contractors should ensure aggregates comply with the limits in these tables to ensure quality concrete.

1. SPECIAL SPECIFICTIONS
(part I )
RECOMMENDED LIMITS FOR
AGGREGATES
USED FOR ALL CONCRETE WORKS
AGGREGATES USED IN ALL CONCRETE WORKS
SHALL COMPLY WITH THE REQUIREMENTS OF
THE FOLLOWING RECCOMENDED LIMITS.
A – Physical and mechanical properties testing. (TABLE -1)
B – Contamination and reactivity testing. (TABLE – 2)
C – Total chloride and sulphate content in concrete. (TABLE -3)
D – Size and gradings of aggregates. (TABLE -4)
E – For more information refer to C.I.R.A Guide.
TABLE – ( 1 ) Recommended limits for the
Physical and mechanical properties of aggregates
Property (and standard which Method of test (and standard Recommended maximum limit (%by
describes it) which describes it) weight)
Grading Sieve analysis Ranges of sizes in table (4)
(BS 882) (Bs 812)
shell content Bs 812-106 Max. 10% of fine aggregate by weight
Shape (Bs 812)-105.2,105.1 Elongation index 25% max.
Flakiness index 25% max.
(Relative density) Weighing in air and in water (BS Not less than 2.5
812)-1995
Water absorption Weighing dry and saturated (BS Coarse Agg.sand 2.5 % max.
812)
Soundness Sulphate resistance (ASTM C-88) Loss after 5 cycles in sulphate solution
(BS 812-121) with
MGSO4 15% max.
Na3SO4 10% max.
Drying shrinkage (BRE Digest (New Series) 35) Shrinkage 0.05% max.
Mechanical properties 10 % fines value For wearing surfaces 100 kN min.
(BS 812-111) Elsewhere 75 kN min.
los Angeles abrasion test For wearing surfaces 25% max.
(ASTM C-131 or C-535) Elsewhere 30% max.
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2. SPECIAL SPECIFICTIONS
TABLE – ( 2 ) Recommended limits for
Contamination and reactivity of aggregates.
Type of contamination or Method of test (and standard Recommended maximum limit (%
reactivity ( and standard which which describes it) by weight)
describes it)
Clay, silt and dust Wet sieving through a Coarse aggregates :
(BS 882, ASTM C-33) 75 - µ m sieve Natural or crushed gravel 1%
(BS 812) Crushed rock 3%
Fine aggregates :
Natural sand or crushed gravel 3%
Crushed rock 5%
Clay lumps (ASTM C-142) Coarse aggregate 2%
(ASTM C-33) Fine aggregate 1%
Organic impurities Comparative setting time and
compressive strength * *
Chlorides as Cl Analysis following acid Coarse aggregates 0.03 %
Extraction Fine aggregate 0.06 %
(BS 812 part 117)
Sulphates as SO3 Analysis following acid Coarse or fine aggregates †
0.4 %†
Extraction
(BS 812 part 118)
Potential alkali (ASTM C-227 and C-289) Potentially reactive material 0.5%
Reactivity max.
- Subject to the total chlorides in mix not exceeding the value given in Table.
† Subject to the total Sulphates in the mix not exceeding the value given in Table
* * Comparison of setting times and 3- day compressive strengths
shows whether a harmful organic content is present. Time
for the concrete to harden should not differ by more than 30 min,
and strength should not be reduced by more than 5%.
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3. SPECIAL SPECIFICTIONS
TABLE – ( 3 ) Recommended limits for
The total chloride and sulphate content in concrete
Type of concrete Max. chloride (Cl) Max. Sulphate (SO3)
Content (% by weight of Content (% by weight of cement)
cement)
Reinforced concrete made 0.15
with Portland cements
containing less than about 4 %
C3A (e.g. sulphate-resisting
Portland cement)
All case 4.0, including the sulphate
Reinforced concrete made 0.30 ion in the cement
with Portland cements
containing 4 % or more C3A
(OPC and ASTM type I and II
usually contain more than 4 %
C3A)
Unreinforced concrete 0.60
TABLE – ( 4 ) Sizes and gradings of aggregates
Description Size (mm) Grading
Single – sized coarse 63 to 40 Normally not more than about 10%
aggregate 40 to 20 of aggregate should be retained on
20 to 10 the maximum size of sieve, and not
10 to 5 more than about 20 % should pass
through the minimum size of sieve.
An aggregate with a maximum size
of 14 mm is also used, mainly for
precast work.
Fine aggregate 5 down Normally not more than 10 %
should be retained on a 5-mm
sieve, and preferably not more than
10 % should pass a 150 µ m sieve
Note: Where the fine aggregates are predominantly of one size (e.g. dune and beach
sands). It may be desirable to blend sands from different sources to obtain an
acceptable grading, provided this does not introduce contamination.
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